fsnotify: use a mutex instead of a spinlock to protect a groups mark list

Replaces the groups mark_lock spinlock with a mutex. Using a mutex instead
of a spinlock results in more flexibility (i.e it allows to sleep while the
lock is held).

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

5 files changed, 15 insertions, 15 deletions

diff --git a/fs/notify/group.c b/fs/notify/group.c
index 354044c47e23..1f7305711fc9 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -95,7 +95,7 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
         init_waitqueue_head(&group->notification_waitq);
         group->max_events = UINT_MAX;
 
-        spin_lock_init(&group->mark_lock);
+        mutex_init(&group->mark_mutex);
         INIT_LIST_HEAD(&group->marks_list);
 
         group->ops = ops;
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index b13c00ac48eb..4e9071e37d5d 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -63,8 +63,8 @@ void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
 {
         struct inode *inode = mark->i.inode;
 
+        BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
         assert_spin_locked(&mark->lock);
-        assert_spin_locked(&mark->group->mark_lock);
 
         spin_lock(&inode->i_lock);
 
@@ -191,8 +191,8 @@ int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
 
         mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
 
+        BUG_ON(!mutex_is_locked(&group->mark_mutex));
         assert_spin_locked(&mark->lock);
-        assert_spin_locked(&group->mark_lock);
 
         spin_lock(&inode->i_lock);
 
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 32447dc06c07..ab25b810b146 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -136,13 +136,13 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
         group = mark->group;
         spin_unlock(&mark->lock);
 
-        spin_lock(&group->mark_lock);
+        mutex_lock(&group->mark_mutex);
         spin_lock(&mark->lock);
 
         /* something else already called this function on this mark */
         if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) {
                 spin_unlock(&mark->lock);
-                spin_unlock(&group->mark_lock);
+                mutex_unlock(&group->mark_mutex);
                 goto put_group;
         }
 
@@ -159,7 +159,7 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
         list_del_init(&mark->g_list);
 
         spin_unlock(&mark->lock);
-        spin_unlock(&group->mark_lock);
+        mutex_unlock(&group->mark_mutex);
 
         spin_lock(&destroy_lock);
         list_add(&mark->destroy_list, &destroy_list);
@@ -232,11 +232,11 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
 
         /*
          * LOCKING ORDER!!!!
-         * group->mark_lock
+         * group->mark_mutex
          * mark->lock
          * inode->i_lock
          */
-        spin_lock(&group->mark_lock);
+        mutex_lock(&group->mark_mutex);
 
         spin_lock(&mark->lock);
         mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE;
@@ -263,7 +263,7 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
         fsnotify_set_mark_mask_locked(mark, mark->mask);
         spin_unlock(&mark->lock);
 
-        spin_unlock(&group->mark_lock);
+        mutex_unlock(&group->mark_mutex);
 
         if (inode)
                 __fsnotify_update_child_dentry_flags(inode);
@@ -277,7 +277,7 @@ err:
         atomic_dec(&group->num_marks);
 
         spin_unlock(&mark->lock);
-        spin_unlock(&group->mark_lock);
+        mutex_unlock(&group->mark_mutex);
 
         spin_lock(&destroy_lock);
         list_add(&mark->destroy_list, &destroy_list);
@@ -296,7 +296,7 @@ void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
         struct fsnotify_mark *lmark, *mark;
         LIST_HEAD(free_list);
 
-        spin_lock(&group->mark_lock);
+        mutex_lock(&group->mark_mutex);
         list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
                 if (mark->flags & flags) {
                         list_add(&mark->free_g_list, &free_list);
@@ -304,7 +304,7 @@ void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
                         fsnotify_get_mark(mark);
                 }
         }
-        spin_unlock(&group->mark_lock);
+        mutex_unlock(&group->mark_mutex);
 
         list_for_each_entry_safe(mark, lmark, &free_list, free_g_list) {
                 fsnotify_destroy_mark(mark);
diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c
index b7b4b0e8554f..f26a348827f8 100644
--- a/fs/notify/vfsmount_mark.c
+++ b/fs/notify/vfsmount_mark.c
@@ -88,8 +88,8 @@ void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
 {
         struct vfsmount *mnt = mark->m.mnt;
 
+        BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
         assert_spin_locked(&mark->lock);
-        assert_spin_locked(&mark->group->mark_lock);
 
         spin_lock(&mnt->mnt_root->d_lock);
 
@@ -151,8 +151,8 @@ int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
 
         mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
 
+        BUG_ON(!mutex_is_locked(&group->mark_mutex));
         assert_spin_locked(&mark->lock);
-        assert_spin_locked(&group->mark_lock);
 
         spin_lock(&mnt->mnt_root->d_lock);
 
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index e76cef75295d..c5848346840d 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -141,7 +141,7 @@ struct fsnotify_group {
         unsigned int priority;
 
         /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
-        spinlock_t mark_lock;           /* protect marks_list */
+        struct mutex mark_mutex;        /* protect marks_list */
         atomic_t num_marks;             /* 1 for each mark and 1 for not being
                                          * past the point of no return when freeing
                                          * a group */